Fig. 4: Characterization of ODLM-based CPL filters.

a Phase delay (left axis) and transmission spectrum (right axis) of a fabricated QWP. b Transmission measured perpendicular to the nanograting orientation (red curve, left axis) and the corresponding linear polarization extinction ratio (blue curve, right axis). c Transmission spectra measured for three devices (designed to operate at three different wavelengths) for LCP and RCP incident light. d Extracted CPER for three devices presented in c. The dimensions measured (length, width, and period, in nanometers) for three devices are 403, 138, and 383 nm (red curve); 438, 153, and 418 nm (blue curve); and 480, 170, and 460 nm (green curve). e Analytically calculated CPER dependence of ODLM device on orientation angle between top QWP and bottom nanograting. The SEM measurement on the left panel shows that the error is less than 0.5°. f FDTD simulation of the CPER dependence on the fused silica spacer layer thickness, corresponding to an optimum value of ~350 nm